Zettomixommwil

Zettomixommwil is equal to \(f_{\underbrace{\psi(\Omega_{\psi(\Omega_{\cdots_{\psi(\Omega)}\cdots})})}_{10^{21}\quad\Omega's}}(10)\) using the fast-growing hierarchy.[1] The term was coined by wiki user Denis Maksudov.

The 4 parts of the name, "zetto", "mix", "omm" and "wil", mean \(10^{21}\), the "mix-" operation, \(\Omega\)-ordinals and Wilfried Buchholz's \(\psi\) function respectively, which form \(\underbrace{\psi(\Omega_{\psi(\Omega_{\cdots_{\psi(\Omega) }\cdots})})}_{10^{21}\quad\Omega's}\) when the "mix-" operation applies. So the full name indicates the ordinal index of the number.